Wiring system for electric ovens



Jan. 16, 1934. R. s. HEISE WIRING SYSTEM FOR ELECTRIC OVENS Original Filed June 27, 1928 4 Sheets-Sheet l H "T77U6W 07." 6606 5 y Jan. 16, 1934.

s. HEISE WIRING SYSTEM FOR ELECTRIC OVENS Original Filed June 27, 1928 v 4 Sheets-Sheet 2 ,fivemio)": 266606 5. Mwf

Jan. 16, 1934. R s HEiSE 1,943,310

WIRING SYSTEM FOR ELECTRIC OVENS Original Filed June 27. 1928 4 Sheets-Sheet 5 Jan. 16, 1934. R. s. HEISE WIRI'EG SYSTEM FOR ELECTRIC OVENS Original Filed June 27, 1 28 4 Sheets-Sheet 4 MK MK wwvN WMN Patented Jan. 16, 1934 UNITED STATES PATENT OFFICE Roscoe S. Heise, Wanseon, Ohio;

executrix of said Roscoe S. Heise Eyda Heise deceased Application June 27, 1928, Serial No. 288,610 Renewed March 6, 1933 8 Claim.

This invention relates to a wiring system for electric ovens and the like of a type which can be readily connected or disconnected and transported from one place to another.

In ovens of this kind it is desirable that the heating units be of as large a size as may conveniently be the case so as to provide for rapid heating of the oven or plate. At the same time the regulations of the Fire Insurance Underwriters limit the amount of current which can be carried by various kinds of electrical equipment such as the flexible cord which it is desired shall be used to connect this electric oven to a standard electrical socket or other similar outlet.

An object of the invention, therefore, is to provide a wiring system for electric ovens of this type which enables a plurality of the electric heating units to be switched in on the line in various combinations but so limits the whole that no more than a predetermined maximum wattage can be exceeded by any possible setting of the switches.

Another object is to provide a set of switches a which are so'combined as to enable one of the heating units to be supplied at all times by an amount of wattage corresponding to the setting of its controlling switch, irrespective of the settings of the switches controlling the other heating units, while the other units shall receive an amount corresponding to the settings of their controlling switches so long only as the sum total of all power flowing through all said units of the oven does not exceed the predetermined total.

These and other objects, as will hereinafter appear, are accomplished by this invention which is fully described in the following specification and shown in the accompanying drawings, in which Figure 1 is a wiring diagram showing three heating units each controlled by a switch, the switch, however, being interconnected and all the switches being turned on full;

Fig. 2 is a similar diagram showing the central switch controlling the top oven heating element turned to a medium position;

Fig. 3 is a view similar to Fig. 2, but showing the central switch turned to a low position;

Fig. 4 is a similar view showing the central switch in an off position;

Fig. 5 is a view of the central controlled switch taken on line 5-5 of Fig. 7;

Fig. 6 is a view of the same on the line 6-6 of Fig. 7;

Fig. 7 is a horizontal longitudinal section of the central switch on the line 7-7 of Fig. 6;

Figs. 8 and 9 are longitudinal sections on the lines 8-8 and 9-9, respectively, of Fig. 6;

Fig. 10 is a perspective view of one of the rotatable contact members of the switch; and

Fig. 11 is a similar view of a companion contact member.

Referring now to the wiring diagram (Figs. 1 to 4), the top oven refractory element consists of two sections A and A which preferably lie upon the top and outside of the oven. The oven represented by the dotted line B has also a top oven refractory element consisting of two sections C and C and a bottom oven refractory element consisting of two sections 1) and D These heating elements, as will later be described, are controlled both individually and in combination by means of switches E, F, G, and H, the switches E and F being connected together so as to operate virtually as a single switch.

The switch E controls the top oven heating element A and A, while the switches G and H control the top oven heating elements C and C and the bottom oven heating elements D and D respectively. The switches E, G and H are identical in construction and operation, and a description, therefore, of switch E will serve also as a description of switches G and H.

The switch E, shown in Figs. 5 to 11, has an insulating block of porcelain 10, or the like, which is secured, as will later be described, to a metallic bracket 11 by means of which it is mounted in an opening in the sheet metal housing (not shown) of the oven. The insulating block 10 is provided with a series of equally spaced posts E E E and E which have flanged bottoms E tapped to receive screws E which pass through the block 10. The post E carries two spaced yieldable sheet metal fingers E which are adapted to spread apart so as to receive a lug E of a rotatable contact member E which is carried by a shaft E rotatably mounted in the center of the block 10. This shaft is rotated by means of a suitable handle E which extends through an opening in the sheet metal cover E This form of switch is well known to the trade under the name of "Diamond H switch, and, therefore, need be described only in such detail as will show how it is used in the present circuit, particularly with the switch F which will later be described, and which combines with the switch E to form a system of control which is unique in the art.

The post E has fingers E which are adapted to engage the lugs E on the contact member E which is also carried by the shaft E the members' E and E being insulated from each other. 110

Likewise the post E (Fig. 9) c ries contact fingers E and E" which lie iix1e same planes as the contact fingers E and respectively. Also the post E has a single contact finger E which is in the same plane as the fingers E and E. The rotatable contact member E also has one other lug E ich is spaced degrees from the lug E rotatable tact member E has 1 at 90 degrees from the lug opposite the lug E The two con act men on the shaft in such a E are placed opposite to E is placed opposite to able members are driven 3:? (see Fig. '7), but this c lugs E and. her and the lug ac ll? ES 2.

known in the not be explained in detaii "Diamond H" switch which is well art.

The switch F consists ci a switch similar to the switch E and set back to back therewith after certain changes have been made therein as will of bolts 13. The shaft s shaft F substantially corre r eling amount. The shaft F has a rotatable ct member F corresponding to the member the switch E and a flat contact member F corresponding to the member E of the switch The switch F has three posts F F and F, which are disposed, as indicated, opposite the post E E and E respectively, or" the switch E. The post F has two contact members and F which align the planes or" the lugs of the contact members F and F respectively. Likewise the post F has two contact fingers F and 36', while the lug F has a single contact finger F There is no post on the switch F opposite the post E of the switch Corresponding numerals will be used to designate similar parts of the various switches, the only change being in the letters G and H with which they are used. Also such parts of the switch F, as correspond to similar parts of the switch E, are also given like numbers. The switch G has ro tatable members G and G similar to the rotatable members E and E of the switch Wiring of the circuit A positive lead 16' is carried to the posts E G and H of the three switches E, G and H, respectively. The post E of the switch E is carried through a lead 17 to one end of the heating section A of the top oven heating element. This section of the heating element is connected to its companion section A by means of a lead 18. The other end of section A is then connected to the negative supply lead by means of a wire 19. This lead 19 connects through a wire 20 with the post E of the switch E and through a wire 21 with the post F of the switch F.

A lead 22 joins the lead 18 midway between the top oven sections A and A and connects it with the post E of the switch E. A lead 23 connects the post G of the switch G with a wire 24 connecting the top oven heater sections C and C The other end of the section C connects through a lead 25 with the post F of the switch F and with the post H of the switch H. The other end of the heater section C connects through a. wire 26 with the post G of the switch G.

One end of the bottom oven heating section position.

D connects through which connects with a rent supply, while the o D connects through a bottom oven heater s turn connects tin-oi H of the switch H.

n D connect" J? of the swit e ource curnd o. the section ie m. 28 with the other T e wire 28 in ..t F of the switch The operation of this wiring system is as follows: In general it will be remembered that with the switches G and H turned to an .ng elements A and A alone. Each rovided with means to be turned to ofif tion, full position in which its heat lg eleu are given the maximum wattage, medium tion in which they are supplied with one-hat power of the full position, and a low po: .ion in which the heating elements are supplied one-fourth the wattage of the full pos For convenience, the actual wattage fur to each heating element is noted on tha" men: in each of the wiring diagrams to 4).

In Fig. 1 all the switches are turned to Current from the positive lead it ters the switch E on the post E through the rotatable contact E to pc and thence through the lead 22 to the he elements A and A Current then tht the heating element A to the lead is and ti back to the negative supply main. Curre t i the lead 22 also passes through the heating post E of the switch, thence able contact E and to the post E and to the lead 20 to the negative supply main.

It will be seen that when the switc-. to the full position, the top oven sect and A are supplied with the maximum of 1 namely, 500 watts each, even though G and H are also turned to their full This is true of the top oven heating units A A which will be given the maximum amount of current when the switch E is turned to the full position no matter what position the swi ches G and H may assume.

Continuing with the wiring diagram of Fig. 1, it will be seen that no current will flow through either of the top oven sections C or C The maximum of power of 250 watts will flow through the section D of the bottom oven heater unit. This is due to the fact that the rotatable switch element H connects the post- H to the post H of the switch H, and this in turn passes current through the lead 29 to the heater section D and thus direct to the negative terminal connection 19. By following up the other leads, it will be seen that they will return upon themselves in such a way as to prevent current passing theret-hrough from the positive to the negative terminals.

Referring now to Fig. 2, the parts are in the position shown in Fig. 1 except that the switch E, F is turned from the full position to the medium position. By so doing, the heater section A is supplied with current substantially as before, while the heater section A is caused to double back upon the positive lead through the contact member E of the switch E. No current, therefore, flows.

It will now be observed that current flows 5 through the heater section B, this current flowing through the leads 30,11, 25, 1", F", 1 and 21, and 19 back to the negative supply main. At the same time current is caused to flow through the heating unit C the return being through the leads 25, F", F", 21 and 19 back to the negative source of current. It will be seen that in Fig. 1 1250 watts only are obtained, 500 watts flowing through each of the units A and A, and 250 watts flowing through the bottom oven unit D. In the setting shown in Fig. 2, 1250 watts flow, and this is divided as follows: 500 watts through the top oven section A 250 watts through the top oven heater unit C and 250 watts each through the bottom oven heating units D and D. Thus the heating units D and D are supplied with a maximum of current in the setting shown in Fig. 2, and not in Fig. 1. This change is brought about by movement of the switch E, F without any change whatever in the switches G and H which primarily control these units.

Referring now to Fig. 3, the switch E, F is turned to the low" position. In this case, cur-- rent from the positive lead 16 flows to the post E, thus flowing through the contact E to the post E, thence to the lead 17, and then through the heating units A and A in series, and thence back to the lead 19 to the negative source of supply. Thus. only 125 watts flows through each of the heating units A and A. At the same time it will be observed that the heater unit of C previously unheated now receives current. This is due to the fact that current will now flow through the leads 26, G G G 31, F F F, 21, and 19, back to the negative source of supply.

In Fig. 4, the switch E, F is turned to the "off position and no current flows through the top oven heating sections A and A. It will also be observed that in Fig. 3, 1250 watts are all that can be obtained, the switches G and H still remaining at the full" position, and the heater units C C D and D getting their maximum of 250 watts each, while the heater units A and A each receive 125 watts.

With the switches as shown in Figs. 3 and 4, the amount 0! power supplied to the units C C and D, D may be correspondingly reduced by manipulation of the switches G or H. It is not necessary, however, that all oi the possible positions and combinations of parts of these switches .be shown. To do so, would needlessly expand this application and make it much more diflicult to read rather than otherwise. It will be understood, however, that in addition to each pair of heating elements C and C being heated at a rate of 250 watts, either singly or in combination, they can also be placed in series as was done with the heating units A and A of Fig. 3, by turning the corresponding controlling switch to thelow position. Thus the top oven heater may use both of the heating units in parallelism, thereby using 500 watts. Either of these sections may be used alone, thereby using 250 watts, or they may be in series, thereby using 125 watts. The switch G controls the top heating elements C C independent of the other switches so long as the top oven heating units A and A are not supplied with more than 125 watts each, as shown in Fig. 3.

It will be seen that I have provided an oven with two heating units and an outside cook ng unit, each of which may be separately controlled by its individual switch, (so long as the total load is not exceeded) and the whole so wired that only a predetermined maximum of power is permitted to flow at any one time, namely, 1250 watts, al-

though the sum total of available heating units is 2000 watts. This enables me to place the oven on the usual lamp cord which can be supplied from any wall socket and still bring it within the requirements of the release of the Insurance Underwriters.

While I have shown and described but a single embodiment of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made which do not depart from the spirit and scope of the invention as covered by the appended claims.

I claim:

1. In combination, three electric heating units each comprising a plurality of heating elements, and means comprising three electrically interconnected switches for connecting heating ele ments of said units in series and in parallel one of said switches having connections to control the various units for any position of the other switches so as to prevent the sum total of power consumed by said units from exceeding a predetermined maximum, each of said switches controlling a different one of said units when the total power does not reach said maximum.

2. In combination, three electric heating units one of which is of a different capacity from the others, each comprising a plurality of heating elements, and means comprising electrically interconnected switches for connecting heating elements of said units in series and in parallel one of said switches having connections to control the various units for any position of the other switches so as. to prevent the sum total of power consumed by said units from exceeding a predetermined maximum, each unit being normally controlled by one of said switches when the total power consumed by the units does not reach said maximum. A 3. In combination, three electric heating units one of which is of a different capacity from the others, each comprising a plurality of heating elements, and means comprising electrically interconnected switches for connecting heating elements of said units in series and in parallel and for modifying the connections to one of the units for a certain position of said switches so as to prevent the sum total of power consumed by said units from exceeding a predetermined maximum less than the total capacity of the units, each unit being normally controlled by one of said switches when the total power consumed by the units does not reach said maximum, said maximumbeing the same for all combinations of settings of said units.

4. In combination, three electric heating units one of which is of substantially twice the capacity of the others, each comprising a plurality of heating elements, and means comprising electrically interconnected switches for connecting heating elements of said units in series and in.

others, each comprising a plurality of heating elements, and means comprising electrically interconnected switches for connecting heating elements of said units in series and in parallel and for modifying the connections to one o! the units for certain positions of said switches so as to prevent the sum total of power consumed by said units from exceeding a predetermined maximum less than the total capacity 01' said units, each unit being normally controlled by one of said switches when the total power consumed by the units does not reach said maximum, one of said units getting its normal amount 0! power corresponding to the setting of its switch irrespective of the settings of the other switches.

6. In combination, three electric heating units one of which is of substantially twice the capacity of the others, each comprising a plurality of heating elements, and means comprising electrically interconnected switches for connecting heating elements of said units in series and in parallel and for modifying the connections to one of the units for certain positions of said switches so as to prevent the sum total of power consumed by said units from exceeding a predetermined maximum less than the total capacity of said units, each unit being normally controlled by one of said switches when the total power consumed by the units does not reach said maximum, said maximum being the same for all combinations of settings of said units, the larger of said units getting its normal amount of power corresponding to the setting of its switch irrespective of the settings of the other switches.

7. In combination, three electric heating units each comprising a' plurality of heating elements, and means comprising three electrically interconnected switches for connecting heating elements of said units in series and in parallel and for modifying the connections to one 01 the units for a certain position of said switches so as to prevent the sum total of power consumed by said units from exceeding a predetermined maximum, each of said switches controlling a different one of said units when the total power does not reach said maximum, said total being less than tulrifitgum oi the maximum power draw of all the 8. In an electrical heating system in combination, three heating units each having two heating elements, one of said units having a capacity of substantially double that of each other unit, a switch for each unit having connections for controlling its corresponding heating elements, the switch for the larger capacity unit being interconnected with the elements 0! the other units whereby when said larger capacity unit is connected for any heating capacity the circuits of the other units will be modified to limit the total consumption not to exceed a maximum amount less than the total capacity of the several units.

ROSCOE S. HEISE. 

